1. Field of the Invention
The present invention relates to a wireless communication system, a method, and a tangible machine-readable medium thereof. More particularly, the present invention relates to a wireless communication system, a method, and a tangible machine-readable medium thereof for transmitting data based on a frame structure of a multi-hop relay standard.
2. Descriptions of the Related Art
With the rapid development of computer networks, various broadband information services are becoming more essential for the information industry. However, due to high costs, only a fraction of all computer users can afford high speed wired broadband services, such as digital subscriber line (DSL) and cable broadband access services. In addition, network telecommunication service providers are looking to expand the coverage range of their wired broadband networks. However, the relevant infrastructure costs for building these wired network prevents them doing so. As a result, many broadband wireless techniques have, hence, become an important alternative. In terms of communication distance, current wireless networks can be classified as follows: wide area network (WAN), metropolitan area network (MAN), local area network (LAN), and personal area network (PAN).
To set up a radio transmission standard for MAN to provide wireless broadband connection as “the last mile” for the telecommunication industry, the IEEE 802.16, a Worldwide Interoperability for Microwave Access (WiMAX), was developed as a wireless transmission standard. After continuous improvement, the IEEE 802.16 has been able to address more market demands, such as various mobile and high speed broadband applications. Moreover, in comparison to other communication techniques, such as Wi-Fi and the third generation mobile communication (3G) technique, the IEEE 802.16 has a larger network bandwidth, lower construction costs, better service quality, better expansibility, and extended usage modes at Wi-Fi hot spots.
Even with its advantages, the communication range and signal quality provided by the IEEE 802.16 are still limited. As a result, the IEEE 802.16j standard Working Group established a mobile multi-hop relay study group in July 2005 for building a mobile multi-hop relay standard (MMR-RS), to establish a multi-hop relay standard (MMR-RS) under the existing IEEE 802.16j standard.
A conventional two-hop relay wireless communication system 1 based on the MMR-RS defined in IEEE 802.16j is illustrated in FIG. 1. The two-hop relay wireless communication system 1 comprises a base station (BS) 101, a relay station (RS) 103, and a plurality of mobile stations (MSs) 105, 107. For brevity, the MSs will be denoted hereinafter as the first MS 105 and second MS 107. One type of frame structure 2 utilized in the aforesaid two-hop relay wireless communication system 1 is illustrated in FIG. 2. The frame structure 2 is allocated by a wireless communication apparatus, such as the BS 101, the RS 103, the first MS 105, or the second MS 107. The frame structure 2 is adapted for data transmission.
The frame structure 2 of the two-hop relay wireless communication system 1 comprises an MS downlink sub-frame 211, an RS downlink sub-frame 213, an MS uplink sub-frame 221, and an RS uplink sub-frame 223. Each of these sub-frames can be used for downlink or uplink data transmission in the two-hop relay wireless communication system 1. The x-axis in FIG. 2 represents the time axis of the frame structure 2, while the y-axis represents the frequency axis.
The MS downlink sub-frame 211 further comprises a pilot message 2111, a frame control header 2113, a downlink MAP 2115, an uplink MAP 2117, and a downlink data allocation 2119. The pilot message 2111 is configured for synchronization between the BS 101 and the second MS 107 or synchronization between the RS 103 and the first MS 105. The frame control header 2113 is configured to describe various parameters of the frame structure 2. The downlink MAP 2115 is configured to broadcast some parameters used for downlink data transmission in the two-hop relay wireless communication system 1, such as connection identifications (CIDs), sub-channel offsets, or time offsets, Similarly, the uplink MAP 2117 is configured to broadcast some parameters used for uplink data transmission in the two-hop relay wireless communication system 1. The downlink data allocation 2119 is configured to transmit data from the BS 101 to the second MS 107 or to transmit data from the RS 103 to the first MS 105. After data transmission of the downlink data allocation 2119, there is a BS/RS-transmission transition gap (BS/RS-TTG) 23 that occurs thereafter.
The RS downlink sub-frame 213 is configured to transmit data from the BS 101 to the RS 103. After transmission of the data of the RS downlink sub-frame 213, there is an RS-receive transition gap (RS-RTG) 24, which occurs after the data transmission.
The MS uplink sub-frame 221 is configured to transmit data from the second MS 107 to the BS 101 or from the first MS 105 to the RS 103. After transmission of the data from the MS uplink sub-frame 221, there is a BS/RS-receive transition gap (BS/RS-RTG) 25 that occurs thereafter.
The RS uplink sub-frame 223 is configured to transmit data from the RS 103 to the BS 101. After transmission of the data of the RS uplink sub-frame 223, the BS-RTG 26 occurs thereafter.
With the frame structure described above, data transmission can proceed successfully in accordance with the IEEE 802.16j standard. For example, the BS 101 and the RS 103 can transmit data respectively via the MS downlink sub-frame 211 and the RS downlink sub-frame 213. However, because data transmission may interfere with other frequency bands at any time, data transmission may be interrupted and thus, not transmitted correctly.
Accordingly, it is important for the mobile communication providers and the mobile communication apparatus manufacturers to find a solution for improving signal immunity against interference and ensuring correct data transmission to extend the communication range of networks using the multi-hop relay standard under IEEE 802.16j.